The late WG Sebald criticised the silence of a generation of German writers about the firebombing of German cities in the second world war. Sebald's On the Natural History of Destruction, published in English translation this month, describes a failure of writers to record this trauma, in all its moral complexity, or to express the national humiliation felt by millions at Germany's defeat. Akira Yoshimura's novel One Man's Justice, originally published in Japan in 1978, provides an illuminating counterpoint to Sebald's book, since it indicates that this taboo was not shared by Japanese writers of an equivalent postwar generation: born in 1927, Yoshimura came of age with the defeat of imperial Japan.

Set in the late 1940s, in the immediate aftermath of Allied victory, the novel follows Kiyohara Takuya, a demobilised officer, through a postwar dystopia of charred cities and starving refugees. Formerly active in defence intelligence, responsible for protecting Japanese cities from US aerial bombardment, Takuya is on the run from likely trial and execution as a war criminal. Acting on a hint, if not an order, from a senior officer as US forces closed in, he and other soldiers had beheaded captured American B29 pilots. Incensed by the thought of US airmen playing jazz and handing around pornographic pictures after bombing raids, Takuya convinced himself that his was an act of just retribution for the pilots' bombardment of civilians - itself a war crime under international law, he maintains - which culminated in Nagasaki and Hiroshima.

As Takuya evades capture for a time, attitudes change towards war criminals. Justice proves relative: not only is it dispensed by the victors, but its severity is determined by changing policy towards the vanquished. As the Korean war makes Japan an even more crucial US ally, old war criminals are rebranded as "victims" of the war who merely obeyed orders - a label Takuya rejects. As he grapples with the stirrings of conscience, troubled by flashbacks of the beheaded airmen, the novel reveals the humiliation and powerlessness of people under occupation. Takuya suffers a sense of physical inferiority before burly GIs, and cringes as soldiers throw candies to the famished Japanese, or perpetrate acts of arbitrary brutality. His waning outrage becomes symptomatic of the transition to a postwar world, and one in which silence about the victors' crimes is assured.

One Man's Justice arguably avoids the issue of Japan's imperial war-mongering, though it clearly records war crimes, such as the use of PoWs for medical experiments. Yet Yoshimura's interest is in the effects of war on an individual's sense of right and wrong. Takuya's humanity is signalled on the first page by his solicitude towards a young boy in a crowded train, head covered in ringworm, whose eyes reveal an "entrusting of his well-being to this man who kept shifting backwards" for him to breathe. The third-person narrative sticks closely to the ex-officer's perceptions, but these are subtly qualified; Takuya interprets his uncle's refusal to harbour him as fearful self-interest, but the older man, a military type of a bygone era, is seen to be appalled by his nephew's actions. Takuya is himself the confused, self-deluding product of a disturbing new moral order, in which many thousands of civilian deaths are seen as justified by military victory, and where the scales of justice are weighted by diplomacy and realpolitik.

Though Yoshimura is the bestselling author of more than 20 books, One Man's Justice is only his second to be translated into English. Canongate published Shipwrecks (1982) in 2001 - also a spare and understated moral tale, about the dehumanising effects of starvation and slavery on a medieval fishing village. It has done well to make available this searching and provocative novel on patriotism, war and defeat.